Conventionally, various ampules made of glass, plastic, or the like have been developed for sealing a drug solution for injection and the like and are practically used. However, the demand for the plastic ampule increases for the safe handling and convenience. In addition, the manufacturing process of the ampule preparation for injection or the like that is the plastic ampule filled with a drug solution employs a so-called blow-fill-seal method in which the step for molding the plastic ampules and the step for filling the content liquid are sequentially performed because the process requires filling the content liquid such as a drug solution as one of the steps.
When a conventional plastic ampule is manufactured by the blow-fill-seal method, as shown in FIG. 6, a plurality of plastic ampules 1a may be formed continuously via thin-wall portions for division 13a to manufacture them as the shape of a plastic ampule block. When the plastic ampules are manufactured as the shape of a plastic ampule block, each of the plastic ampules 1a is divided along the thin-wall portion for division 13a formed in the plastic ampule block to be used. Furthermore, in the conventional plastic ampule 1a, a head portion 6a is formed continuously to a mouth portion 3a of a body portion 2a via a cut-off portion 10a, and a hollow is formed in the head portion 6a to communicate with the mouth portion 3a (that is, with the body portion 2a). Then, in order to reliably open the mouth portion 3a of the body portion 2a, the cut-off portion 10a that communicates the head portion 6a with the body portion 2a is formed so as to have a neck-down shape.
In the conventional plastic ampule 1a shown in FIG. 6, as an enlarged view shown in FIG. 4(B), the head portion 6a is formed so as to have a substantially pentagon as the cross section shape along the flat surface of a knob portion 9a, and the hollow portion 8a is formed to have substantially the same shape in the head portion 6a. Furthermore, the lower end of the head portion 6a is formed continuously to the mouth portion 3a via the cut-off portion 10a, and when the knob portion 9a that is integral with the head portion 6a is twisted with fingers to cut the head portion 6a off from the mouth portion 3a, an opening portion 4a is formed at the upper end of the mouth portion 3a. In this case, the opening portion 4a is similarly formed at the lower end of the head portion 6a. The lower end of the head portion 6a is formed so as to have a substantially straight line that is parallel to the cut-off portion 10a. Furthermore, when the plastic ampule is manufactured by the blow-fill-seal method or the like, as shown in FIG. 7(B), the lower end (near the cut-off portion) of the head portion 6a that is formed continuously to the cut-off portion 10a is formed to have a wall thickness p thinner than the wall thickness q of the upper end (near the cut-off portion) of the mouth portion 3a (p<q).
Furthermore, FIG. 4(C) shows another conventional plastic ampule in which a head portion 6b is formed to have a substantially semicircle shape as the cross section shape along the flat surface of a knob portion 9b, and a hollow portion 8b is formed to have the same shape in the head portion 6b. In the plastic ampule, the lower end of the head portion 6b is formed continuously to a mouth portion 3b via a cut-off portion 10b. When the knob portion 9b that is integral with the head portion 6b is twisted with fingers to cut the head portion 6b off from the mouth portion 3b, an opening portion 4b is formed at the upper end of the mouth portion 3b, and the opening portion 4b is formed at the lower end of the head portion 6b. Also in this ampule, the lower end of the head portion 6b is formed so as to have a substantially straight line that is parallel to the cut-off portion 10b. Also in this case, as with the case of the plastic ampules in FIG. 6, when the plastic ampule is manufactured by the blow-fill-seal method or the like, as shown in FIG. 7(C), the lower end (near the cut-off portion) of the head portion 6b that is formed continuously to the cut-off portion 10b is formed to have a wall thickness p thinner than the wall thickness q of the upper end (near the cut-off portion) of the mouth portion 3b (p<q).
A similar plastic ampule to the plastic ampule 1a shown in FIG. 6 is disclosed in Patent Document 1. Patent Document 1 discloses that a plurality of plastic ampules are formed continuously via connection portions to form a plastic ampule block and that each of the plastic ampules has a fused portion between the mouth portion and the head portion (grip portion). In the plastic ampule of Patent Document 1, the connection portion is formed from the container body portion to the grip portion and the fused portion does not have a reduced diameter. Furthermore, the head portion is formed to have a substantially pentagon as the cross section shape along the flat surface of the grip portion, and the lower end of the head portion is formed to have a substantially straight line that is parallel to the fused portion, but there is no description about the wall thickness near the fused portion.
As a conventional plastic ampule, Patent Document 2 discloses a plastic ampule in which a plurality of synthetic resin ampules are formed continuously via thin-wall portions to form a synthetic resin ampule block, in each of the synthetic resin ampules, a twist-off portion is formed between a shoulder portion and a narrow neck portion, and a thin-wall portion is formed on a plate portion that is formed upwardly and downwardly across the twist-off portion, along the straight line on the twist-off portion. The narrow neck portion in Patent Document 2 is formed to have a substantially pentagon as the cross section shape along the flat surface of the plate portion, and the lower part of the narrow neck portion has a reduced diameter as an inverted cone shape. As a result, a whole narrow neck portion does not have a bowl shape, and, as shown in FIG. 3 of the literature, the twist-off portion has almost the same wall thickness as that near the upper part.
As a conventional plastic ampule, Patent Document 3 discloses a plastic ampule in which a breaking site is formed between a head having a toggle and a neck of an ampule body and in which the toggle is twisted or bent to separate the head from the neck along the breaking site. The head in Patent Document 3 is formed to have an ellipse as the cross section shape along the flat surface of the toggle. Furthermore, as shown in FIG. 3 of the literature, the head has almost the same wall thickness as that of the neck.